JIM H

Hello everyone. I have a 94 Z28 LT1. I have an issue and I'm hoping maybe some of you have experience with the symptoms/issues
that I'm having and can give a bit of advice based on your experience. I have taken a look at just about every component that I
can think of except for 1 or 2 that I haven't had a chance to check out. I just can not figure this out.

The main issue that I have is if I operate the throttle anywhere above 60% or so the car just stumbles, sputters and bogs down.

If I accelerate with less than 60% throttle, it moves really well.

Other observations:

The idle is a little bit rough and a little more lopey than I remember it being. It isn't stalling.

When the engine is at 1800-2000 RPM under load the car vibrates, almost like it is not firing on all cylinders. Above 2000 RPM
it is just fine, below 1800 it is just fine.

I did run the 94/95 SCAN program (Thanks, Gary!). I don't see anything too funky in the data. But maybe one of you might so I
am attaching the data file.

Injuneer

You need to provide basic info about your car:

https://www.camaroz28.com/forums/lt1...nature-879835/

Need to know trans type, any engine mods, reprogramming, etc.

In checking various things, have you checked the fuel pressure? Have you inspected the rubber elbow between the MAF sensor and the throttle body for tears or being loose?

Then I can take a look at the files. Might take a while because I just picked up three other files to review.

JIM H

-Year of vehicle (and make if not a 4th Gen F-Body): 94 Z28, LT1
-Year of engine, if not identical to the year of vehicle: 94
-Type of transmission: Automatic
-All major modifications that affect the performance of the vehicle: None. It is stock.

[QUOTE=In checking various things, have you checked the fuel pressure?[/QUOTE]
Yes. I replaced the fuel pump and filter last fall. The fuel pressure at the fuel rail looks good.

[QUOTE=Have you inspected the rubber elbow between the MAF sensor and the throttle body for tears or being loose?[/QUOTE]
Yes. It is intact.

[QUOTE=Then I can take a look at the files. Might take a while because I just picked up three other files to review.[/QUOTE]

Sorry for the late response. I work in the fireworks industry and the last few weeks have been pretty busy.

JIM H

Just checking to see if you had a chance to check out the data files. Thanks!

Injuneer

When you never got back with info about your car for a month I stopped looking at them. I had put a huge amount of work looking at one file, but ut seemed pointless to continue. Right now I'm recovering from eye-surgery performed on 8/3/21. I can't spend a lot of time looking at bright screens full of fine print.

JIM H

Sorry for not getting back for a while. I work 16-18 hour days from about 2 weeks before Memorial Day until the 4th with no days off so everything gets set aside other than eating and sleeping.

Sorry to hear you had to have eye surgery. Obviously I don't want you to look at the files while your eyes are still healing. I hope they heal fully and quickly for you.

Without reviewing them again, do you remember if anything stood out?

Thank you,
James

Injuneer

I understand you were busy, but look at it from my point of view. You obviously came here looking for my help, with your data logs. I started working on them, and you disappeared. Unfortunately that happens a lot here. Newbie shows up, asks for help, and never responds after I offer a response. All you had to do was take 5 minutes to check the screen and tell me you were busy.

It was running lean, forcing some big long term fuel corrections to add extra fuel. It was running lean in power enrichment (PE) mode. That's basically when you go heavy on the throttle. Also huge amount of knock retard, possibly because of the lean condition.

You indicate the fuel pressure "looks good". Did you actually check it out on the road with the engine under heavy load/high RPM? If not, under what conditions did you measure the fuel pressure, and what were the actual numbers?